Prime Minister Anthony Albanese has been touring flood-affected areas in Victoria and NSW and said the continuing rain will drive prices higher.

"Tragically, there had been such a good harvest anticipated in wheat, in fruit and vegetables, in so many of the products that the Victorian food basin ... is such a rich area, as well as in areas like poultry," Mr Albanese told ABC Melbourne.

Agriculture Minister Murray Watt joined the prime minister on Monday to assess the flood damage around Forbes in central western NSW.

He told a media conference prime agricultural regions had been "very badly impacted by the repeated floods".

"It's likely that these floods are going to have a cost of living impact on people because of the impact of prices of fruit and vegetables," Mr Watt said.

The federal department of agriculture is trying to work out what financial impact the flooding will have on agricultural production.

The federal and state governments are also discussing extra support for impacted farmers.

Victorian Premier Daniel Andrews conceded there would "almost certainly" be food production impacts stemming from the flooding.

"This is the food bowl of our state and the food bowl of our nation, whether it be in terms of fruit and veg and cropping more broadly," he told reporters.

In Victoria's north, where floodwaters continue to rise, farmers are counting the costs, especially in the food bowl around Shepparton.

Victorian Farmers Federation horticulture president Nathan Free told AAP fruits such as apples, pears, peaches, nectarines and plums have all been badly hit.

"If they get flooded now, you possibly may not have a crop the coming season," he said.

Prue Milgate of Ettrick Farms at Serpentine in the state's northwest said 98 per cent of their farm was flooded. About one-third of their crop cannot be salvaged, equating to hundreds of thousands of dollars in losses.

Beyond that, farmers are facing long-term livestock health issues given animals have been standing in water, and few solutions are available since Serpentine was cut off by washed-out roads, Ms Milgate said.

"(People in Loddon Shire) had sewage flowing through their houses, yet they're not being declared as a disaster zone," she said.

The farmers federation president Emma Germano said it was too early to gauge the full effect on food availability and prices, but there would be significant supply chain disruption.

Farmers in Victoria had been expecting a bumper winter crop but analysts say they now face volume and quality downgrades due to the excessive rains.

RaboBank issued its Australian winter crop forecast on Monday and found a significant impact on yields of low-lying crops with many submerged in central and northern Victoria.

Flooding in parts of both NSW and Victoria has led to washed-out fields and crops that cannot be harvested.

GrainGrowers chairman Brett Hosking said lentil crops had been badly affected by the Victorian flooding, while hay has been "completely ruined" in the state's northwest.

RaboBank's Dennis Voznesenski said NSW bore the brunt of flooding from excessive rain earlier in the year.

"Winter crops like wheat, barley and canola were already downgraded in NSW and we could see even more cropping land impacted now," he told AAP.

Tasmanian Farmers and Graziers Association chief executive Hugh Christie flagged the destruction was significant across key farming areas in the state's north and northwest.

There was also flooding in other areas including the northeast and parts of the Central Highlands.

"These impacts have ranged from loss of crops and infrastructure ... through to the stripping of top soil on highly impacted properties," Mr Christie told AAP.

The full extent of the damage will only become apparent as levels recede and the impact of water logging on the emergence of crops is shown in coming weeks, he said.

Australian Associated Press